Liquid level indicator



c. c. SILSBY, JR

LIQUID LEVEL INDICATOR File d Jan. 5, 1950 FEB. 161954 INVENTOR.CHRISTOPHER 0. SI LSBY,JR.

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Patented Feb. 16, 1954 moon) LEVEL mmoA'roa Christopher C. Silsby, Jr.,Euclid, Ohio, assignor to Diamond Alkali Company, Cleveland, Ohio, acorporation of Delaware Application January 5, 1950, Serial No. 136,935

' 3 Claims. (Cl. 73-302) This invention relates to a combination liquidfeed-liquid level indicator device for reservoirs in hydrodynamicsystems, and more particularly relates to a combination liquidfeed-liquid level indicator device for electrolytic cells in whichaqueous solutions are subjected to electrolysis to give at least onegaseous product.

The present invention is used in hydrodynamic systems which include astream of liquid fed continuously or intermittently to a reservoir fromwhich liquid and/or gases are continuously or intermittently withdrawn.Such systems include electrolytic cells, for example, cells in whichwater is subjected to electrolytic decomposition to oxygen and hydrogen,or in which a solution of an electrolyte, such as sodium chloridesolution, is electrolytically decomposed to chlorine, hydrogen, andsodium hydroxide. The conventional construction of cells for theelectrolysis of a sodium chloride brine includes regularly spaced anodesadjacent perforated cathodes supporting a liquid permeable diaphragm. Apositive pressure of electrolyte solution is maintained on the anodeside of the diaphragm by maintaining a higher level of electrolytesolution in the anode compartment than that in the cathode compartment,whereby the diaphragm is held in place and a liquid permeable-gasimpermeable separator is maintained between the anode and cathodecompartments of the cell.

It is essential to efficient and safe operation of such cells topreclude the intermixing of hydrogen and chlorine, since suchintermixing requires subsequent separation to purify the gases, or may,if the proper proportions of the gases arepresent in the mixture, resultin destructive explosions. However, when the liquid level in a cell isnot maintained above the uppermost level of the cathode structure,intermixing of the gases evolved (chlorine and hydrogen) results, withattendant difi'iculties heretofore noted. It is for this reason thataccurate determinations of the liquid level within the cells must bemade at frequent intervals.

The liquid level indicators previously employed in conjunction withelectrolytic cells have been for the most part of the simple U-tubemanometer type, one leg of which extends into the anolyte solutionwithin the cell and the other of which is open to the atmosphere. Insome applications of the U-tube manometer, the U- tube is mounted atopthe cell and one leg of the U-tube is opened to the atmosphere and theother extends vertically into the anolyte liquor to the point below themean or normal liquid level therein and immediately above an anode,whereby chlorine gas evolved at the anode displaces anolyte solution forthe extension of the manometer leg, and hydrostatic pressure exerted bythe body of anolyte solution above the open end of the extension of themanometer leg is transferred through the gas in the leg to theindicating liquid in the U-tube.

The difficulty with such devices has been that the indicated level ofthe'liquid within the cell was erroneous because of the added effect ofthe pressure of gas above the body of anolyte solution, the level ofwhich is to be indicated, being transferred and exerted upon theindicating liquid in the manometer.

One of the objects of the present invention is to combine the functionsof a liquid level indicator for an electrolytic cell with a simple feeddevice therefor.

Another object of the invention is to provide a liquid level indicatorwhich gives an accurate, direct indication of the. level of liquid in anelectrolytic-cell during the operation thereof.

A further object of the invention is to combine a liquid feed device andliquid level indicator for electrolytic cells, in which indicator thefeed solution itself isthe level indicating fluid.

Still another object of the invention is to provide an integratedcombination of an accurate, direct reading liquid indicator withasolution feed device for use in electrolytic cells for the electrolysisof sodium chloride brine solution.

Another object of the invention is to provide a liquid level indicatorfor electrolytic cells which gives an accurate, direct indication of thelevel of the body of electrolyte solution within the cell either whenthe cell is operating on an electric circuit or when. the circuitthrough the cell is broken.v These and other objects will be apparent tothose skilled in the art from the discussion of the inventionhereinafter and from the drawing, in which the single figure is avertical section of the feed system and level indicator as applied to anelectrolytic cell, the cell being shown in fragmentary section.

In the drawing, l is the cover of an electrolytic cell for theelectrolysis of sodium chloride brine, to which cell brine solution 4 isfed from manifold header line 2 through take-off 6; take-01f 6 leads tostream disintegrator 8, having means l2 for breaking up the continuityof the brine stream I6 andultimately forming small discrete droplets l8;stream disintegratorl opens into collector cage l4 through seal Ill;collector cage [4 is in fluid connection with tube 22, supported by seal20, which leads through conduits 24, 25, and 30 to the anolytecompartment of cell i. Manometer 25 has tubular connector 34 at thelowermost portion thereof, to which one leg of conduit 26 is attached bymeans of liquid-tight seal 33; leg 36 of manometer 25 is continued andextended by means of tubes 40 and 44, entering cell l at 58 above theanolyte level. Leg 38 of manometer 25 is continued and extended by tubes42 and 45 to level It immediately above. an anode 50; continuations 44and 46 of tubes 40 and 42 enter cell i throughgas-tight seal 48.

The operation of the device of the presentinvention is as follows:

A sodium chloride brine solution 4 ilowsf-rom manifold header 2 throughtake-oil 6 and stream disintegrator 8 into collector cage I4; droplets Iof the brine solution are collected at the base of cage M as a stream,whichleaves cage l4 through tube 22; the stream passes through conduits2:4, 26, and 33 into cell I at 3:2, supplementing the body of anolytesolution therein, which body of solution is maintained in cell 1 at asuitable level h above the anodes and cathodes; an electric currentpassing from anode 519 through the anolyte solution causes the formationof bubbles 54 of chlorine gas, a small portion of which passes into theopen end of tube 46 and displaces therefrom any anolyte solution whichmay have risen therein; tube 46 as. shown enters the cell bodyvertically but may, if desired, enter at an angle from the vertical solong as the slope of tube 45 has an appreciable vertical component sothat gas evolved at anode 59' may rise therein and displace any liquidanolyte which may for one reason or another have entered tube 45. Aportion of the feed stream enters manometer 25 from conduit 28 throughconnector 34 and rises in leg 36 of manometer 25 to level e, and in legas, to level e.

The distance represented by A ('e' -e) indicated by manometer 25 isequal to distance B (h"-h the height of anolyte solution above the openend of tube 46, by virtue of the fact that the liquid in manometer '25.is of substantially the same specific gravity as that of the body ofanolyte solution in cell I, and moreover, by the fact that theindication given by the difierential'of the levels e and 'e" inmanometer 25 equals the pressure of the hydrostatic head of solutionabove the open end of tube 46 (all liquid therein having been displacedby the gas evolved "at anode 50), plus the pressure of the body of gaswithin the free space above the body of anolyte solution, minus thatpressure, since it is also exerted through tubes 40 and 44 and leg 35 tothe indicating liquid in manometer 25. The indication shown by menometer25 is thereby compensated for pressure in the space above the anolyte inthe cell. Therefore, only the effect of the hydrostatic pressure (h'h)of the solution above the open end of tube 46 is obtained, whereby theheight of the anolyte solution in cell i above it is obtained directlyat manometer 2 5 as distance A.

When the manometer 25 is mounted in juxtaposition to the cell and thelegs 36 and 38 thereof extend above and below the maximum and minimumliquid levels allowable in the anode compartment, the indication of themanometer is accurate whether the cell is operating on "circui or is ohcircuit? When the cell is 'oil circuit, i. e. when no electric currentflows "from the allude :to thecathcde, anolyte solution grad ually risesin tube 46 to the level prevailing in the anode compartment and theindicator liquid in less 36 and 38 then assumes a common levelcorresponding to the actual level of the anolyte solution, since no gasis evolved from the surface of the anode to displace anolyte solutionfrom tube 46, and since the anolyte compartment and manometer 25 are influid connection both as to the liquid and the gas phases therein.

Although the level indicator device is shown in the drawing injuxtaposition to an electrolytic cell, it may be situated more remotelyfrom said cell so long as the legs 36 and 38 extend above and below themaximum and minimum levels at-tamed by the anolyte in the cell duringits operation. Preferably, however, the manometer 25 is not situated soremotely from the cell that temperature variations in the atmosphere caneffect appreciable changes in the volume of gases in tubes 40 and 44 andin tubes 42 and as, whereby erroneous deduction as to the liquid levelin the cell could result. Also, the junction of oonduit 25 and connector34 may be positioned otherwise than as shown in the drawing. Forexample, connector 34 may be placed along either of the legs 36 and 38of the manometer 25 above the lowermost portion thereof, so long as theentry of connector 34 into the legs is lower than the minimum liquidlevel therein. In addition, manometer 25 may be positioned laterally atan angle from the vertical in order to give an apparent exaggeration ofthe distance A and render the indication more exact and more easilyperceptible at a visual angle different from the horizontal.

Where it is desired to transfer the information obtained at themanometer 25 to some place re mote therefrom, translating devices, suchas optical systems, electrical impulse systems, and the like, may beemployed. However, the present device as shown has been foundwell-suited to commercial operations involving a large number ofelectrolytic cells within the same building, since an operator need onlywalk between rows of cells to make rapid and accurate observations ofthe level of liquid in the banks of such cells in a matter of minutesand thereby rapidly obtain a complete and accurate perspective ofoperating conditions obtaining throughout an entire bank of cells.

It is preferable in assembling the apparatus of the present inventionthat collector cage l4 be of transparent material, such as glass,synthetic transparent plastics, and the like, in order that directobservations of the disintegration of the feed stream may be had toinsure isolation of the cell electrically. Likewise, legs 36 and 38 ofmanometer '25 are preferably of transparent materials, such as glass,transparent synthetic plastics, and the like. Also, in any variation ofthe device legs 35 and 38 of manometer 2-5 preferably extend above andbelow the maximum and minimum levels which the electrolyte solution inthe cell attains during the course of the operation thereof, in orderthat an accurate visual determination of the liquid level in the cellmay be made.

While there has been illustrated and described in detail an embodimentof the invention, the described invention is not intended to beunderstood as limiting the scope of the invention as it is realized thatchanges therewithin are possible and .it is further intended that eachelementor instrunientality recited in any of the following iclaimsiis tobe understood as referring to all equivalent elements orinstrumentalities for accomplishing substantially the same results insubstantially the same or equivalent manner, it being intended to coverthe invention broadly in whatever form its principle may be utilized.

What is claimed is:

1. An electrolyte level indicating device for an electrolytic cellincluding means to introduce a stream of electrolyte to the cell, and amanometer, the lower portion of which is in liquid connection with saidmeans said manometer having a pair of pressure differential indicatinglegs, one of said legs terminating in said cell beneath the electrolytelevel therein and above a gas-producing electrode, and the other of saidlegs terminating in said cell above the liquid level of saidelectrolyte.

2. A liquid level indicator for an electrolytic cell including a conduitmounted to feed a stream of electrolyte solution to said cell, and aU-tube manometer in liquid connection with said conduit in the lowerportion of said manometer and having continuations of the arms thereofextending into said cell, one of said continuations extending into thebody of solution in said cell to a region directly above thegas-evolving surface of a gas-evolving electrode and the other of saidcontinuations extending into the free space of said cell above theliquid therein.

3. An electrolyte level indicating device for a chlorine-producingelectrolytic cell including a U-tube manometer mounted in juxtapositionto said cell and extending above and below the normal liquid level to bemaintained therein, continuations of the arms of said manometerextending into the interior of said cell, one of said continuationsextending through the roof of said cell to below said liquid level andto a point immediately above an anode and the other of saidcontinuations extending into the free space of the anode compartment ofsaid cell, and a tubular member fluidly connecting the lowermost portionof said manometer and said conduit.

CHRISTOPHER C. SILSBY, Jr.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,808,023 Dienner June 2, 1931 1,924,495 Gustine Aug. 29, 19332,248,006 MacCallum July 1, 1941 2,486,207 Richards Oct. 25, 1949

